JP2014040890A - Hub unit bearing with seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hub unit bearing with a seal that can maintain sealability for a long period by preventing a pressure difference from being generated between a sealed internal space and an external space and suppressing a foreign matter from entering the internal space.SOLUTION: A cover 30 which covers the whole filter 27 is provided on an outer side of a filter 27 made of porous polytetrafluoroethylene capable of blocking a liquid such as water and oil although a gas such as air can permeate. A pinhole 33 which penetrates a bottom plate part 32 of the cover 30 in an axial direction is bored in a center part of the bottom plate part 32 by a processing method which produces no chip, for example, by sticking a pin.

Description

  The present invention relates to a hub unit bearing for rotatably supporting automobile wheels with respect to a suspension device.

  Conventionally, in hub unit bearings that support automobile wheels, in order to prevent external dust and muddy water from entering the inside of the bearing and to prevent the grease enclosed in the bearing from leaking to the outside. In addition, a hub unit bearing with a seal in which seal members are disposed at both ends of the bearing is used. In this sealed hub unit bearing 1, as shown in FIG. 4, an outer ring 2 which is a stationary ring is supported and fixed to a knuckle of a suspension device (not shown) by a mounting flange 6 formed on the outer peripheral surface thereof. Also does not rotate. A hub 3 that is a rotating wheel is disposed concentrically with the outer ring 2 on the inner diameter side of the outer ring 2, and the hub 3 rotates when the automobile is used. The hub 3 includes a hub body 4 and an inner ring 5, and a rotation flange 7 is formed on the outer peripheral surface of the hub body 4 in the axial direction, and a wheel is fixed to the rotation flange 7. In the state where the hub unit bearing is attached to the vehicle, the outer side in the width direction of the vehicle (left side in FIG. 4) is referred to as “outer side”, and the central side in the width direction of the vehicle (right side in FIG. 4) is referred to as “inner side”.

  In addition, on the inner peripheral surface of the outer ring 2 that is a stationary peripheral surface, double-row outer ring raceways 8 and 8 that are stationary raceways are formed, and the outer peripheral surface of the intermediate portion of the hub body 4 that is a rotational peripheral surface and Inner ring tracks 9, 9 each of which is a rotating track are formed on the outer peripheral surface. A plurality of rolling elements 10 and 10 are arranged between the outer ring raceways 8 and 8 and the inner ring raceways 9 and 9, respectively, so that the hub 3 is rotatable. Furthermore, each rolling element 10 and 10 is hold | maintained so that rolling is possible by the holder | retainers 11 and 11, respectively. In the example of FIG. 4, a tapered roller is used as the rolling element 10, but a ball may be used as the rolling element in order to reduce rotational torque and save fuel.

  Further, a seal device 13 is attached between the inner peripheral surface of the inner end portion of the outer ring 2 and the outer peripheral surface of the inner end portion of the inner ring 5, and the outer peripheral portion inner peripheral surface of the outer ring 1 and the intermediate portion outer peripheral surface of the hub body 4. A sealing device 12 is attached between them. These sealing devices 12 and 13 close and seal the openings at both ends of the internal space 14 formed between the inner peripheral surface of the outer ring 2 and the outer peripheral surface of the hub 3 in which the rolling elements 10 and 10 are arranged. doing.

  By the way, the hub unit bearing is used in a state where a disk brake or the like constituting a braking device of an automobile is attached in an environment exposed to outside air. Therefore, when the temperature of the hub unit bearing rises suddenly under conditions such as intense braking operation or a long downhill, a pressure difference is generated between the bearing inner space sealed by the sealing device and the outer space (outside air). Due to this pressure difference, the seal lip constituting the seal device may be deformed and stuck to the sliding surface to increase the rotational torque, or in the worst case, the seal lip may be swollen and a gap may be generated. . On the other hand, when an air passage hole such as a notch is provided in a part of the seal device to adjust the internal pressure of the bearing, dust and moisture (oil) etc. intrude into the internal space together with the air, and the hub unit bearing This will lead to a decrease in the service life.

  As a prior art for improving this part, as described in Patent Document 1, by providing a valve body made of a material capable of passing air and blocking moisture and oil in the opening formed in the sealing device, The pressure inside and outside of the bearing can be adjusted, and moisture can be prevented from entering to ensure the life of the bearing.

JP 2004-052924 A

  However, in this prior art, as a valve body, a porous polytetrafluoroethylene sheet represented by Gore-Tex (registered trademark) is used as a filter for ensuring air circulation while blocking moisture and oil. However, this filter is directly exposed to the bearing outer space. For this reason, in bearings such as hub unit bearings where muddy water on the road surface directly splashes, fine mud enters the porous portion of the porous polytetrafluoroethylene and becomes clogged, or air permeability is lost. Has a problem that the wall portion of the hole is covered with fine mud, the water repellency and oil repellency characteristic of porous polytetrafluoroethylene are inhibited, and the filter function cannot be maintained for a long time. In addition, the valve body itself may be destroyed due to a collision with a bouncing stone or the like.

  The present invention solves the problems of the conventional sealing device as described above, prevents a pressure difference from being generated between the sealed internal space and the external space, and allows foreign matter to enter the internal space. An object of the present invention is to provide a hub unit bearing with a seal that can suppress the above and maintain the sealing performance for a long time.

In order to solve the above problems, a sealed hub unit bearing according to the present invention is provided with a stationary wheel having a double-row stationary track on a stationary circumferential surface, and a double-rowed circumferential surface provided concentrically with the stationary wheel. A rotating wheel having a rotating track, a plurality of rolling elements provided between each of the stationary tracks and the rotating tracks, respectively, a stationary peripheral surface of the stationary wheel, and a rotating periphery of the rotating wheel. A seal ring that closes the axial end opening of the internal space existing between the ring and the seal ring. The seal ring is fixed to the axial end of the stationary ring, and the core metal. A seal member fixed to the entire circumference of the seal ring, and the seal ring is provided with an opening that communicates the internal space and the external space, and the opening is closed with a filter having a property of allowing gas to pass but not liquid to pass. It is out.
In particular, in the sealed hub unit bearing of the present invention, the filter is a sheet made of porous polytetrafluoroethylene, and a cover made of rubber and covering the entire filter is provided on the outer side of the filter. And a valve is formed on the bottom plate portion by a processing method that does not generate chips, and the valve opens and closes due to a change in pressure in the internal space.

Further, the cover has a bottomed cylindrical shape and a substantially U-shaped cross section, and a pinhole is provided in the bottom plate portion.
Alternatively, the cover has an elliptical dome shape and a circular cross section, and a slit is provided in the bottom plate portion.

According to the present invention, it is possible to prevent a pressure difference from occurring between the sealed internal space and the external space, and to suppress the entry of foreign matter into the internal space and maintain the sealing performance over a long period of time. A sealed hub unit bearing with a seal can be provided.
That is, the outer space side of the filter that does not allow the passage of moisture or oily liquid while allowing gas such as air to pass through is covered with a rubber cover so that the muddy water splashed from the road surface, etc. Is prevented from adhering directly to the filter. Therefore, since the surface of the filter is always kept clean, gas permeability, water repellency and oil repellency can be maintained over a long period of time. Furthermore, a pinhole or a slit is formed in the bottom plate portion of the rubber cover by a processing method that does not generate chips, and the internal space and the external space are When a pressure difference occurs between the two, the bottom plate portion is elastically deformed by the pressure. Accordingly, a tensile stress is generated around the pinhole (or slit) to widen the pinhole (or slit), thereby allowing the cover to be ventilated and adjusting the pressure in the internal space.

It is (a) fragmentary sectional view of the seal ring which shows 1st Embodiment, (b) The modification of a pinhole, (c) Another modification of a pinhole. It is the (a) partial sectional view of the exhaust seal ring which shows 2nd Embodiment, (b) The enlarged view of a slit. It is a fragmentary sectional view of the same seal ring for intake. It is sectional drawing which shows the structure of the conventional hub unit bearing with a seal | sticker.

[First example of embodiment]
FIG. 1 shows a first example of an embodiment of the present invention. The feature of this example is that the structure of the seal ring 13 that closes the axial end opening of the internal space 14 in which the rolling elements are installed is devised. The structure and operation of the other parts are the same as in the case of the example of the conventional structure shown in FIG. 4 described above. Hereinafter, the characteristic part of this example will be mainly described.

  As shown in FIG. 1A, the seal ring 13 a that closes the axially inner end opening of the internal space 14 includes a core metal 20 and a seal member 21 that are each formed in an annular shape, and a filter mechanism 26. Become. Of these, the metal core 20 is integrally formed in a substantially U-shaped cross section by performing punching processing such as press processing and plastic processing on a metal plate. Then, the annular cylindrical portion 24 formed radially outward of the cored bar 20 is press-fitted and fitted to the inner peripheral surface of the inner end portion in the axial direction of the outer ring 2 via the sealing material 21, thereby sealing ring 13 a is fixed to the outer ring 2.

  The sealing material 21 is made of an elastic material such as an elastomer such as rubber, and is joined to the core metal 20 by vulcanization bonding. A seal lip 22 is provided on the inner diameter side of the seal member 21, and the tip edge of the seal lip 22 is slidably contacted with the outer peripheral surface of the inner ring 5 over the entire circumference, and the seal lip 22 is attached to the inner ring by a garter spring 23. The outer end opening of the inner space 14 is sealed by pressing toward the outer peripheral surface of the inner space 14.

Furthermore, an opening 25 that communicates the internal space 14 and the external space is provided in a radially outer portion of the seal ring 13a, and this opening 25 is for adjusting the pressure between the internal space and the external space. The filter mechanism 26 including the filter 27 and the cover 30 is closed. A filter main body 28 that is a synthetic resin or metal and has a hollow annular shape as a whole, which constitutes the filter mechanism 26, is adhesively fixed to the inner peripheral surface of the opening 25. Inside the filter main body 28 in the axial direction, the filter 27 for adjusting the pressure between the internal space 14 and the external space.
It is blocked by The filter 27 can pass a gas such as air, but is formed in a sheet shape with a material capable of blocking liquid such as moisture and oil, and has gas permeability, adhesiveness, toughness, and weather resistance. For example, porous polytetrafluoroethylene (registered trademark: Gore-Tex)
Etc. are used.

  Further, a cover 30 that covers the entire outside of the filter 27 is provided on the inner side in the axial direction of the filter body 28. The cover 30 is made of a rubber material and has a bottomed cylindrical shape with a substantially U-shaped cross section, a disc-shaped bottom plate portion 32, and a cylindrical connecting portion 34 that extends in the axial direction from the outer peripheral edge of the bottom plate portion 32. And a fitting ring portion 31 formed at an end portion of the connecting portion 34 opposite to the bottom plate portion 32. Then, the cover 30 is fixed to the filter body 28 by fitting and fixing the fitting ring part 31 in an annular locking groove 29 formed on the inner end surface in the axial direction of the filter body 28. . In addition, the fitting method to the locking groove 29 may be either external fitting or internal fitting, or may be both fitting, and an adhesive may be used in combination.

  At the center portion of the bottom plate portion 32, at least one pin hole 33 penetrating the bottom plate 32 in the axial direction is opened by a processing method that does not generate chips such as piercing with a pin. Since the pinhole 33 is processed by a method that does not generate chips, the pinhole 33 is closed in a state where no stress is applied to the bottom plate portion 32, in other words, in a state where the bottom plate portion 32 is not deformed. Air cannot pass through this pinhole 33. When a pressure difference occurs between the internal space 14 and the external space of the bearing due to a rapid temperature change or the like, the bottom plate portion 32 changes into a convex shape or a concave shape in the axial direction, and tensile stress is generated around the pinhole 33. As a result, the pinhole 33 expands and the inside space 14 is adjusted to adjust the internal pressure. Thereafter, when the pressure difference between the internal space 14 and the external space disappears (pressure adjustment is completed), the deformation of the bottom plate portion 32 is removed, and the pinhole 33 is closed.

Furthermore, the thickness of the connecting portion 34 is made thinner than the thickness of the bottom plate portion 32, whereby stress acting on the fitting ring portion 31 propagates to the bottom plate portion 32, or the bottom plate is caused by molding shrinkage. The portion 32 is prevented from becoming a tensile stress field.
Further, the bottom plate portion 32 needs to have a certain thickness in order to maintain its shape. If the thickness is too thick, the pinhole 33 may not be easily opened and closed. In such a case, as shown in FIG. 1B, by providing coaxial recesses 35, 35 on both sides in the axial direction of the bottom plate portion 32 and forming a pinhole 33 at the bottom of the recess 35, The opening / closing sensitivity of the pinhole 33 can be increased. Further, as shown in FIG. 1C, a recess 35 can be provided only on one side of the bottom plate portion 32, and a pinhole 33 can be formed on the bottom thereof. As described above, since the pinhole 33 is disposed at the back of the concave portion 35, it is possible to further suppress the infiltration of water and dust from the pinhole 33.

With the configuration as described above, the sealed hub unit bearing 1 according to the present invention prevents a pressure difference from occurring between the sealed internal space 14 and the external space, and allows foreign matter to enter the internal space 14. And the sealing performance can be maintained over a long period of time.
That is, the outer space side of the filter 27 that does not allow the passage of a gas such as air while allowing a gas such as air to pass through is covered and protected by the rubber cover 30, so that it jumps off the road surface. The raised muddy water or the like is prevented from adhering to the filter 27. Therefore, since the surface of the filter 27 is always kept clean, the gas breathability, water repellency and oil repellency can be maintained over a long period of time. Further, the pinhole 33 is formed in the bottom plate portion 32 of the rubber cover 30 by a processing method in which chips are not generated, and when a pressure difference is generated between the internal space 14 and the external space (the temperature rises). When the internal pressure in the internal space increases, the bottom plate portion 32 is elastically deformed by the pressure and changes into a convex shape (or a concave shape), thereby generating a tensile stress around the pinhole 33 and generating the pinhole 33. The cover 30 can be vented and the pressure in the internal space can be adjusted.

[Second Example of Embodiment]
2 and 3 show a second example of the embodiment of the present invention. In the case of the present embodiment, the seal ring 13b shown in FIG. 2 has an exhaust filter mechanism 26a that discharges the air in the internal space 14 to the outside, and FIG. A seal ring 13c having a filter mechanism 26b for intake is shown, and the direction in which air can pass is regulated by the shapes of the covers 30a and 30b.

  FIG. 2 shows an exhaust filter mechanism 26a. The cover 32a of this example is formed of a rubber material, and has an elliptical dome shape that is convex to the outside of the bearing (axially inside) and has a circular cross section in the radial direction, and an elliptical shape that is convex to the outside. A dome-shaped bottom plate portion 32a and a fitting ring portion 31 formed around the entire periphery of the outer peripheral edge of the bottom plate portion 32a are provided. The fitting ring portion 31 is fitted and fixed in a locking groove 29a formed in the filter body 28a, thereby covering the entire outer space side of the filter 27. In addition, the fitting method to the latching groove | channel 29 can be external fitting, internal fitting, and can also be both fitting, and can also use an adhesive agent together.

  And the slit 36 which penetrates the said baseplate part 32a to an axial direction is formed in the center part of the said baseplate part 32a with the processing method which does not generate | occur | produce chips, such as cutting with a cutter. Since the slit 36 is processed by a method that does not generate chips, the slit 36 is normally closed (a state in which no stress is applied to the bottom plate portion 32a), and air does not pass through the slit 36. Can not. When the pressure in the internal space 14 rises, the bottom plate portion 32a has a convex shape on the outer side, so that the slit 36 can be opened to release air. On the other hand, when the pressure in the internal space 14 decreases, the slit 36 does not open and air does not pass through. Furthermore, the slit 36 is closed tightly against splashing of muddy water or the like from the outside of the bearing, preventing muddy water and dust from entering.

  FIG. 3 shows an intake filter mechanism 26b. The cover 32b of this example is also made of a rubber material and has a bottomed cylindrical shape as a whole. The cover 32b has an elliptical dome-like bottom plate 32b that protrudes toward the bearing inner side (axially outer side), A cylindrical wall portion 37 extending axially inward from the periphery, a cylindrical connecting portion 34a extending axially outward from the outer peripheral edge of the bottom plate portion 32a, and an axially outer end portion of the connecting portion 34a And a fitting ring portion 31 formed in the above. The fitting ring portion 31 is fitted and fixed in a locking groove 29a formed in the filter body 28a, thereby covering the entire outer space side of the filter 27. And the slit 36 which penetrates the said baseplate part 32b to an axial direction is formed in the center part of the said baseplate part 32b by the processing method which does not generate | occur | produce chips, such as cutting with a cutter. In the intake cover 30b, since the bottom plate portion 32b has a concave shape on the outside of the bearing, the slit 36 is opened only when the pressure in the internal space decreases, and the pressure in the internal space 14 is reduced to atmospheric pressure. It is possible to increase up to. Further, against splashing of muddy water from the outside of the bearing, a wall portion 37 that protects the periphery of the bottom plate portion 32b is provided to prevent intrusion of muddy water and dust.

  In the case of the present embodiment as described above, the direction in which air can pass is determined by the shape of the covers 32a and 32b, and therefore, the filter mechanisms 26a and 26b are provided at two places where the phases of the seal ring 13b are different. Of course, when there is a specific purpose such as preventing an increase in the internal pressure of the bearing internal space due to the press-fitting of the seal ring, the exhaust filter mechanism 26a shown in FIG. 2 or the intake filter mechanism 26b shown in FIG. It is also possible to wear either one of these.

The hub unit bearing with seal shown in FIG. 4 is a third generation hub unit bearing, but the seal ring of the present invention can also be applied to various hub units. For example, an outer ring having a double row outer ring raceway on the inner peripheral surface, a plurality of inner rings having inner ring races respectively opposed to the outer ring raceways, and a rolling element interposed between the double row outer ring raceways, It can be applied to a first generation hub unit bearing having no flange and mounting flange. Furthermore, the present invention can be applied to a second generation hub unit bearing in which only the mounting flange is formed on the outer peripheral surface of the outer ring in contrast to the first generation hub unit bearing. Also, the present invention can be applied to an outer ring rotating hub unit bearing in which the outer ring is a rotating ring.
Furthermore, the filter mechanisms 26, 26a, 26b, which are the features of the present invention, are not limited to the seal rings of the above-described embodiments (FIGS. 1 to 3), and the filter mechanisms 26, 26a, 26b can be incorporated. Applicable to all types of seals.

  The bearing with a seal according to the present invention can be suitably used as a bearing used in a muddy water environment and under conditions with a large temperature change, for example, a wheel-supporting buff unit bearing that rotatably supports a vehicle wheel. .

DESCRIPTION OF SYMBOLS 1 Hub unit bearing with seal 2 Outer ring 3 Hub 4 Hub body 5 Inner ring 6 Mounting flange 7 Rotating flange 8 Outer ring race 9 Inner ring race 10 Rolling element 11 Cage 12 Seal device 13, 13a, 13b, 13c Seal ring 14 Inner space 20 core Gold 21 Seal member 22 Seal lip 23 Garter spring 24 Cylindrical part 25 Opening 26, 26a, 26b Filter mechanism 27 Filter 28, 28a Filter body 29, 29a Locking groove 30, 30a, 30b Cap 31 Fitting ring part 32, 32a 32b Bottom plate part 33 Pinhole 34, 34a Connecting part 35 Recessed part 36 Slit 37 Wall part

Claims (3)

A stationary wheel having a double row stationary track on the stationary circumferential surface, a rotating wheel provided concentrically with the stationary wheel and having a double row rotational track on the rotating circumferential surface, the both stationary tracks and the both rotating tracks; A plurality of rolling elements provided so as to be able to roll, respectively, and a seal for closing an axial end opening of the internal space existing between the stationary peripheral surface of the stationary wheel and the rotating peripheral surface of the rotating wheel The seal ring includes an annular cored bar fixed to the axial end of the stationary ring, and a seal member fixed to the entire circumference of the cored bar. In a sealed hub unit bearing provided with an opening that communicates between the internal space and the external space, and the opening is closed with a filter having a property that gas passes but liquid does not pass,
The filter is a sheet made of porous polytetrafluoroethylene, and the outer side of the filter is provided with a cover made of rubber that covers the entire filter and having a bottom plate portion, and a processing method that does not generate chips on the bottom plate portion. A hub unit bearing with seal, wherein a valve is formed, and the valve is opened and closed by a change in pressure in the internal space.   The hub unit bearing with seal according to claim 1, wherein the cover has a cylindrical shape with a bottom and a substantially U-shaped cross section, and a pin hole is provided in the bottom plate portion.   The hub unit bearing with seal according to claim 1, wherein the cover has an elliptical dome shape and an arc-shaped cross section, and a slit is provided in the bottom plate portion.

Images